Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More
Hierdie gesprek is in die argief. Vra asseblief 'n nuwe vraag as jy hulp nodig het.
In die argief

Thunderbird 115.10.1 (64-bit) fails to send SMTP messages

mozilla414

Since Thunderbird was upgraded to 115.10.1 (64-bit), it now fails to send SMTP messages with the following error.

Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) ***.mail.pairserver.com was lost in the middle of the transaction. Try again.

This affects all six(6) accounts in Thunderbird, all of them can receive and edit e-mail messages; however, all of them fail to send e-mail messages.

Prior versions of Thunderbird have worked with this configuration for many years.

Other e-mail clients such as Evolution do not have this issue and I have confirmed with my provider that Thunderbird is no longer sending e-mails.

Any thoughts on how to roll back Thunderbird until this issue is resolved?

Since Thunderbird was upgraded to 115.10.1 (64-bit), it now fails to send SMTP messages with the following error. Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) ***.mail.pairserver.com was lost in the middle of the transaction. Try again. This affects all six(6) accounts in Thunderbird, all of them can receive and edit e-mail messages; however, all of them fail to send e-mail messages. Prior versions of Thunderbird have worked with this configuration for many years. Other e-mail clients such as Evolution do not have this issue and I have confirmed with my provider that Thunderbird is no longer sending e-mails. Any thoughts on how to roll back Thunderbird until this issue is resolved?

All Replies (5)

Changing releases doesn't usually fix things -- but sometimes they do. The prior version is at https://ftp.mozilla.org/pub/thunderbird/releases/115.10.0/ or you could upgrade to 115.11.

Thanks; however, sudo apt install thunderbird indicates: thunderbird is already the newest version (1:115.10.1+build1-0ubuntu0.23.10.1).

Well, 115.11 was released on May 14th.

 https://www.thunderbird.net/en-US/thunderbird/115.11.0/releasenotes/

115.11.0 seems to resolve the SMTP issue.


Well, maybe not so much. I added back the additional accounts and it does not work again... Only supports a single account at the moment.

Gewysig op deur mozilla414

This forum is full of folk using ubuntu that are not aware their new version 24 of the product is using sandboxed snap installs of applications which are causing all sorts of issue with remote anything really. See https://ubuntu.com/core/docs/security-and-sandboxing